[1.7.x] Fixed #21630 -- Simplified management command discovery

import collections

import imp

from importlib import import_module

from optparse import OptionParser, NO_DEFAULT

import os

        return []

def find_management_module(app_name):

    """

    Determines the path to the management module for the given app_name,

    without actually importing the application or the management module.

    Raises ImportError if the management module cannot be found for any reason.

    """

    # TODO: this method is only called from get_commands() which has already

    # imported the application module at that point.

    parts = app_name.split('.')

    parts.append('management')

    parts.reverse()

    part = parts.pop()

    path = None

    # When using manage.py, the project module is added to the path,

    # loaded, then removed from the path. This means that

    # testproject.testapp.models can be loaded in future, even if

    # testproject isn't in the path. When looking for the management

    # module, we need look for the case where the project name is part

    # of the app_name but the project directory itself isn't on the path.

    try:

        f, path, descr = imp.find_module(part, path)

    except ImportError as e:

        if os.path.basename(os.getcwd()) != part:

            raise e

    else:

        if f:

            f.close()

    while parts:

        part = parts.pop()

        f, path, descr = imp.find_module(part, [path] if path else None)

        if f:

            f.close()

    return path

def load_command_class(app_name, name):

    """

    Given a command name and an application name, returns the Command

    if not settings.configured:

        return commands

    app_names = [app_config.name for app_config in apps.get_app_configs()]

    for app_name in reversed(app_names):

        try:

            path = find_management_module(app_name)

            commands.update({name: app_name for name in find_commands(path)})

        except ImportError:

            pass  # No management module - ignore this app

    for app_config in reversed(list(apps.get_app_configs())):

        path = os.path.join(app_config.path, 'management')

        commands.update({name: app_config.name for name in find_commands(path)})

    return commands